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Author: Chunhua Deng Publisher: ISBN: Category : Languages : en Pages : 179
Book Description
This study is focused on the chemical composition and cloud nucleation ability of marine aerosol based on two cruise researches over Pacific Ocean and North Atlantic Ocean respectively. Implications of CLAW hypothesis and the factors influencing its validity are analyzed for the contemporary era with ever-increasing pollution. The pacific cruise started from Punta Arenas, Chile and ended in Seattle, WA during March-April of 2010. Raman microspectroscopy (RMS) was employed to identify the chemical composition and mixing conditions of single particles collected. By analyzing multiple particles in a collected ensemble, the degree of external/internal mixing of particles was also determined. Atmospheric aerosol concentration, cloud condensation nuclei (CCN) concentration, and chlorophyll a concentration in the underlying water (a metric for phytoplankton biomass in the ocean), were also measured. Our results indicate that long chain organic molecules were prevalent in the marine aerosol samples throughout the cruise. Long chain organic compounds tended to stay mixed with other organic and inorganic components. The influence of marine organic aerosols on cloud nucleation ability is analyzed. The North Atlantic cruise started from Woods Hole, MA and returned back to the same location during June-July 2011. The cruise passed through a wide range of conditions, including areas of high phytoplankton biomasses and extremely high DMS levels (over 1800 pptv). Aerosol concentration, cloud condensation nuclei (CCN) concentration, particle size distribution, as well as surface seawater and atmospheric DMS concentrations were performed simultaneously during the cruise. HYSPLIT back trajectories were used to classify air mass origins. Even though continental sources increased the total aerosol population, it depressed the effective CCN concentrations possibly due to the competition in particle growth. Continuous high CCN and elevated DMS concentrations over the open ocean occur concurrently, which can be explained by enhanced nucleation and condensational growth of aerosols in marine boundary layer (MBL) resulting from the DMS oxidation or primary aerosols from the sea surface. Our data also indicated that uncertainties remain in sea spray aerosol production flux function, especially for particles with dry diameter smaller than 200 nm. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151824
Author: Chunhua Deng Publisher: ISBN: Category : Languages : en Pages : 179
Book Description
This study is focused on the chemical composition and cloud nucleation ability of marine aerosol based on two cruise researches over Pacific Ocean and North Atlantic Ocean respectively. Implications of CLAW hypothesis and the factors influencing its validity are analyzed for the contemporary era with ever-increasing pollution. The pacific cruise started from Punta Arenas, Chile and ended in Seattle, WA during March-April of 2010. Raman microspectroscopy (RMS) was employed to identify the chemical composition and mixing conditions of single particles collected. By analyzing multiple particles in a collected ensemble, the degree of external/internal mixing of particles was also determined. Atmospheric aerosol concentration, cloud condensation nuclei (CCN) concentration, and chlorophyll a concentration in the underlying water (a metric for phytoplankton biomass in the ocean), were also measured. Our results indicate that long chain organic molecules were prevalent in the marine aerosol samples throughout the cruise. Long chain organic compounds tended to stay mixed with other organic and inorganic components. The influence of marine organic aerosols on cloud nucleation ability is analyzed. The North Atlantic cruise started from Woods Hole, MA and returned back to the same location during June-July 2011. The cruise passed through a wide range of conditions, including areas of high phytoplankton biomasses and extremely high DMS levels (over 1800 pptv). Aerosol concentration, cloud condensation nuclei (CCN) concentration, particle size distribution, as well as surface seawater and atmospheric DMS concentrations were performed simultaneously during the cruise. HYSPLIT back trajectories were used to classify air mass origins. Even though continental sources increased the total aerosol population, it depressed the effective CCN concentrations possibly due to the competition in particle growth. Continuous high CCN and elevated DMS concentrations over the open ocean occur concurrently, which can be explained by enhanced nucleation and condensational growth of aerosols in marine boundary layer (MBL) resulting from the DMS oxidation or primary aerosols from the sea surface. Our data also indicated that uncertainties remain in sea spray aerosol production flux function, especially for particles with dry diameter smaller than 200 nm. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151824
Author: Meagan Julia Kerry Moore Publisher: ISBN: 9781124543123 Category : Languages : en Pages : 281
Book Description
Atmospheric aerosol particles are a major component of the troposphere and affect regional and global atmospheric chemistry and climate. The size and chemistry of these particles influences the warm and cold cloud nucleation ability and optical properties of the aerosol particles. This dissertation investigates the atmospheric chemistry of aerosol particles and their role in warm cloud nucleation through a combination of laboratory experiments and field measurements. The effect of organics on the cloud condensation nuclei (CCN) activity of sea spray aerosols is described in Chapter 2. Sea spray aerosol produced by bubbling solutions composed of simplistic mixtures of NaCl and oleic acid or SDS had a significant effect on CCN activity, even in very small amounts; while artificial seawater solutions containing microorganisms, the common cyanobacteria (Synechococcus) and DMS-producing green algae (Ostreococcus), produced particles containing ~34 times more carbon than the particles produced from pure ASW, with no significant change observed in the overall CCN activity. During the fall of 2007 and 2008, over 300,000 acres burned in San Diego County wildfires. The resulting particle chemistry and estimated hygroscopicity during these wildfire events are explored in Chapter 3. The contribution of wildfire emissions were much larger and played a more significant role in affecting cloud condensation nuclei and total particle concentrations in 2007 than in 2008. The overall particle hygroscopicity during the biomass burning dominated periods was very similar; however in 2008, the particle hygroscopicity was dominated by local sources rather than biomass burning, due to the much smaller particle size mode. Owens Lake is one of the largest sources of PM2.5 in the Western Hemisphere, producing highly soluble dust plumes, and therefore there is great potential for those particles to impact cloud formation and possibly precipitation in the region. Chapter 4 explores particle chemistry and estimated hygroscopicity at Owens Lake. No significant change in particle hygroscopicity or CCN activity occurred concurrently with the change in mixing of particle classes during two different dust events at Owens Lake; indicating that the large dust particles were most likely completely CCN active and the smaller particles are likely dictating the hygroscopicity, as most of the dust particles are large enough and would activate to become CCN regardless of their hygroscopicity. The Cloud Indirect Forcing Experiment (CIFEX) took place to study the influence of aerosols on cloud properties at Trinidad Head, a coastal site in northern California representing clean marine air with periodic long-range transport. Chapters 5 & 6 explore particle chemistry, mixing state, optical properties and estimated hygroscopicity during CIFEX. Our measurements demonstrate how changes in hygroscopicity and optical properties evolve over time in the atmosphere as a function of particle chemistry and the mixing state of the aerosol. Two distinct oxalate events with enrichment of oxalate on different particle types and sizes suggest two separate sources of oxalate.
Author: Beth Friedman Publisher: ISBN: Category : Aerosols Languages : en Pages : 151
Book Description
Aerosol-cloud interactions represent a significant uncertainty with respect to radiative forcing and future climate change. Both particle composition and size play key, yet poorly understood, roles in determining the cloud nucleating capabilities of aerosols. The following describes ambient and laboratory measurements of cloud condensation nuclei (CCN) and ice nuclei (IN) measurements from a variety of sources, with the goal of understanding how composition and size interact in forming cloud droplets and ice crystals and the potential importance of aerosol composition and atmospheric aging processes on constraining uncertainties associated with the cloud nucleating properties of aerosols. Motivated by the anthropogenic emissions of soot particles as well as the potential properties of aged soot particles, ice formation and droplet activation of soot particles of various size and composition were studied. Generated soot particles were coated with a variety of atmospherically relevant acids of varying solubility properties. The particles were also exposed to ozone in order to simulate atmospheric oxidation and aging. A custom-built ice chamber was utilized to show that both uncoated and coated soot particles comparable to those generated in our studies are unlikely to significantly contribute to the global budget of heterogeneous IN at relevant atmospheric temperatures. This result is emphasized by comparison to an efficient ice nucleus, such as mineral dust. Coatings and oxidation by ozone also did not significantly alter the ice nucleation behavior of soot particles but aided in the uptake of water, suggesting the altered composition of a hydrophobic particle is important to take into account for cloud droplet activation. To assess the importance of particle composition in cloud droplet activation, measurements of CCN concentrations, single particle composition, and number size distributions were conducted at a high-elevation research site. The temporal evolution of detailed single particle chemical composition was compared with changes in CCN activation. A variety of particle types were observed; CCN activation largely followed the behavior of the sulfate-containing particle types; biomass burning particles also contained hygroscopic material that impacted CCN activation. The observed particles were largely aged; few local sources contributed to the particle composition due to the high elevation of the site. The results were also interpreted in terms of the assumed hygroscopicity of free tropospheric aerosol. As a further examination of the impacts of aging processes on aerosol hygroscopicity measurements of CCN concentrations, aerosol composition, and number size distributions were conducted during the winter season from of a variety of air masses, including aged marine, continental, and urban sources. Based on the measured chemistry and size properties of the ambient aerosol, CCN concentrations were predicted in order to assess the amount of composition detail necessary to explain droplet activation. Direct measurements of the composition of the activated droplets were also conducted with a novel technique to separate activated droplets from un-activated aerosol. Results suggest the importance of inorganic species in droplet activation, with non-oxidized organic species having negligible impacts on total aerosol hygroscopicity. Using the same novel separation technique, measurements of the single particle composition of activated droplet residual particles were determined at an urban site in the summertime, with similar air mass trajectories as the previous wintertime site, as well as influence from local urban aerosol sources. As a function of atmospheric supersaturation conditions the composition of activated droplet residual particles was compared to the ambient aerosol composition. The study was utilized to determine the level of composition and size detail required to describe droplet activation at a site with similar aged air mass trajectories to the previous study.
Author: Colin D. O'Dowd Publisher: Springer Science & Business Media ISBN: 1402064756 Category : Science Languages : en Pages : 1275
Book Description
Atmospheric particles are ubiquitous in the atmosphere: they form the seeds for cloud droplets and they form haze layers, blocking out incoming radiation and contributing to a partial cooling of our climate. They also contribute to poor air quality and health impacts. A large fraction of aerosols are formed from nucleation processes – that is a phase transition from vapour to liquid or solid particles. Examples are the formation of stable clusters about 1 nm in size from molecular collisions and these in turn can grow into larger (100 nm or more) haze particles via condensation to the formation of ice crystals in mixed phase or cold clouds. This book brings together the leading experts from the nucleation and atmospheric aerosols research communities to present the current state-of-the-art knowledge in these related fields. Topics covered are: Nucleation Experiment & Theory, Binary, Homogeneous and Heterogeneous Nucleation, Ion & Cluster Properties During Nucleation, Aerosol Characterisation & Properties, Aerosol Formation, Dynamics and Growth, Marine Aerosol Production, Aerosol-Cloud Interactions, Chemical Composition & Cloud Drop Activation, Remote Sensing of aerosol & clouds and Air Quality-Climate Interactions
Author: M. Kulmala Publisher: Elsevier ISBN: 0080537820 Category : Science Languages : en Pages : 995
Book Description
This volume is a collection of papers presented at the 14th International Conference on Nucleation and Atmospheric Aerosols, Helsinki, 26 - 30 August 1996. The first conference of this series took place in Dublin (1955); second, Basel and Locarno (1956); third, Cambridge (1958); fourth, Frankfurt am Main and Heidelberg (1961); fifth, Clermont-Ferrand and Tolouse (1963); sixth, Albany and University Park (1966); seventh, Prague and Vienna (1969); eighth, Leningrad (1973); ninth, Galway (1977); tenth, Hamburg (1981); eleventh Budapest (1984); twelfth, Vienna (1988); thirteenth, Salt Lake City (1992). The Atmospheric Aerosol conference has been held jointly with the Nucleation Symposium since 1988 in Vienna in order to stimulate contacts between researchers in these closely related fields. The broad nature of the meeting and the scientific program resulted in 32 countries submitting papers for presentation. Covering both experimental and theoretical studies these papers are divided amongst the chapters on Nucleation, Stratospheric Aerosols and Ice Nucleation, Tropospheric Aerosols and Aerosol-Cloud-Climate Interaction. In addition to these contributed papers invitations to present a plenary lecture on topics of particular current interest were accepted by P.J. Crutzen, J. Gras, J.L. Katz, A.A. Lushnikov, D. Oxtoby, J.E. Penner, Th. Peter, F. Raes, S.E. Schwartz, R. Strey and G. Vali. These plenary papers together with the contributed papers provide a well-balanced perspective of the current research over the entire field and highlight some important issues.
Author: Kathryn J. Mayer Publisher: ISBN: Category : Languages : en Pages : 291
Book Description
Aerosol-cloud interactions are one of the largest sources of uncertainty in our understanding of the Earth's climate system. In order to develop better predictive models and understand how the climate will respond to future changes in atmospheric composition, we must determine the sources and nature of aerosols which serve as cloud condensation nuclei (CCN), thus influencing the properties of clouds. Oceans cover 70% of the Earth's surface and represent a major source of atmospheric aerosols. Sea spray aerosol (SSA) is formed by the action of breaking waves, whereas secondary marine aerosols (SMA) are formed from the oxidation products of gases emitted from the oceans. Biological activity in seawater (i.e. the life, death, and interactions of marine phytoplankton, bacteria, and viruses) can significantly affect the chemical composition of SSA through processing of dissolved organic matter and SMA through the emission of volatile gases. This dissertation investigates the cloud-relevant properties of SSA and SMA generated using ocean-atmosphere simulators in the laboratory, with a specific emphasis on the influence of biological activity in seawater on the properties of these aerosols. For the first time, SMA was produced from the oxidation of the headspace gases of a phytoplankton bloom grown in natural seawater, enabling measurements of its chemical composition and CCN activity. Overall, these studies show that the formation and properties of SMA are much more sensitive to biological activity in seawater than SSA. In addition, the chemical composition of SMA is highly dependent on the extent of photochemical oxidation, with a distinct shift from organic-rich to sulfate-rich composition in response to increased atmospheric aging. This change in SMA composition leads to a significant change in its hygroscopicity. These results suggest that the properties of SMA evolve temporally in the atmosphere, which has implications for CCN concentrations and cloud properties over the oceans.
Author: Lilian A. Dove Publisher: ISBN: Category : Languages : en Pages : 25
Book Description
Bubble bursting at the ocean surface generates smaller film-burst particles and larger jet drop particles that differ in composition. The chemical composition of sea spray aerosols is an important parameter for the evaluation of their impact on the global climate system. This study investigates the role of particle chemistry on the heterogeneous ice nucleation potential of laboratory-generated sea spray aerosols. Cultures of Procholorococcus, a highly abundant marine phytoplankton species, were used as a model source of organic sea spray aerosols. Results show that smaller particles generated from the lysed Procholorococcus cultures were organically enriched and effectively activated as ice nucleating particles at warmer temperatures and lower supersaturations than larger particles. The role of chemical composition in the activation of the particles was studied by measuring the nucleation abilities of single component organic molecules that mimic proteins, lipids, and carbohydrates in Procholorococcus. Amylopectin, agarose, and aspartic acid exhibited nucleation behaviors similar to particles generated from Procholorococcus cultures. Therefore, carbohydrates and proteins with numerous and well-ordered hydrophilic functional groups may determine the ice nucleation potential of organic sea spray aerosols.
Author: Seong-Gi Moon Publisher: ISBN: Category : Languages : en Pages :
Book Description
This study focuses on the analysis of atmospheric particles sampled from two different field campaigns: the field study at a cattle feeding facility in the summer from 2005 to 2008 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. A ground site field study at a representative large cattle feeding facility in the Texas Panhandle was conducted to characterize the particle size distributions, hygroscopicity, and chemical composition of agricultural aerosols. Here, a first comprehensive dataset is reported for these physical and chemical properties of agricultural aerosols appropriate for use in a site-specific emission inventory. The emission rate and transport of the aerosols are also discussed. In addition, mixing ratios of total and gaseous ammonia were measured at the same field in 2007 and 2008. Measurements such as these provide a means to determine whether the fugitive dust emitted from a typical large feedlot represents a health concern for employees of the feeding operation and the nearby community. Detailed chemical composition of aircraft-sampled particles collected during ISDAC was studied. Filter samples were collected under a variety of conditions in and out of mixed phase and ice clouds in the Arctic. Specifically, particles were sampled from a mixed-phase cloud during a period of observed high concentrations of ice nuclei (IN), a biomass plume, and under relatively clean ambient conditions. Composition of particles was studied on a particle-by-particle basis using several microspectroscopy techniques. Based on the elemental composition analysis, more magnesium was found in Arctic cloud residues relative to ambient air. Likewise, based on the carbon speciation analysis, high IN samples contained coated inorganics, carbonate, and black or brown carbon particles. In the samples collected during a flight through a biomass burning plume, water-soluble organic carbon was the dominant overall composition. Due to their hygroscopic nature, these organics may preferably act as cloud condensation nuclei (CCN) rather than IN. Other ambient samples contained relatively higher fractions of organic and inorganic mixtures and less purely water-soluble organics than found in the biomass particles. The most likely source of inorganics would be sea salt. When present, sea salt may further enhance ice nucleation.
Author: Chunhua Deng
Author: Chunhua Deng
Author: Meagan Julia Kerry Moore
Author: Beth Friedman
Author: Colin D. O'Dowd
Author: Kenneth A. Rahn
Author: M. Kulmala
Author: Kathryn J. Mayer
Author: Lilian A. Dove
Author: Gusztáv Götz
Author: Seong-Gi Moon